Disposable electrochemical sensor strip

ABSTRACT

A disposable electrochemical sensor strip is provided. The sensor strip includes an isolating sheet having at least a through hole, at least a conductive raw material mounted in the through hole, a metal film covered on the conductive raw material to form an electrode which comprises an electrode working surface for processing an electrode action, and an electrode connecting surface, at least a printed conductive film mounted on the isolating sheet and having a connecting terminal for being electrically connected to the electrode connecting surface, and a signal output terminal for outputting a measured signal produced by the electrode action.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 10/462,904, filed Jun. 17, 2003 which is relevant to U.S.application Ser. Nos. 11/109,169 and 10/354,684, which are incorporatedby reference as if fully set forth.

FIELD OF INVENTION

The present invention relates to a disposable electromechanical sensorstrip, and more particular to a structure and manufacturing method of asheet type strip which is suitable for examining an analyte in a fluidsample, for example, the concentration of glucose in human blood, andthe concentration of a uric acid.

BACKGROUND

Generally, utilization of a noble metal as an electrode material for anelectrochemical sensor can achieve a high stability and a highreproducibility of detection and is a well-known technique in the fieldof electrochemistry. But, in the sensor, the only demand of the noblemetal is a surface of an electrode, and other surfaces of the noblemetal are unnecessary. Especially, for a disposable strip, the noblemetal surfaces rather than the electrode are all squandered. The mainpurpose of the present invention is to provide a structure and amanufacturing method of a low-price metal electrode in a disposableelectrochemical sensor strip for significantly reducing the demand ofthe noble metal and further reducing the cost.

The metal electrode according to the present invention also can beapplied in various metal-catalyzed electrodes (not only noble metals)with a direct catalysis, besides in a noble electrode without chemicalinterference. The disposable electrode and the sensor according to thepresent invention can be suitable for all kinds of electrochemicaldetection electrodes, biosensors, fluid biochemical sensor (e.g.,sewage, insecticide concentration, and heavy metal sensor strips),domestic medical application (e.g., blood glucose, uric acid, andcholesterol sensor strip).

The principle of electrochemical sensor has been developed and appliedin detecting all kinds of fluid, biochemical ingredients. Anelectrochemical sensor may have different configurations for conformingto different functions. Please refer to FIG. 1. FIG. 1 shows that abasic framework of an electrochemical detecting device 10 includes thefollowing components:

1. A container 12 for containing a fluid sample to be an electrochemicalmeasure region 13.

2. A chemical reagent 14 for chemically reacting with an analytecontained in the fluid sample 11 and generating an output signal with anelectric parameter, wherein the electric parameter corresponds to abiochemical ingredient of the analyte contained in the fluid sample 11.For example, if the fluid sample 11 is human blood and the analyte isglucose, the chemical reagent 14 is basically a glucose oxidase and acomplex thereof.

3. Plural testing electrodes, as shown in FIG. 1, a counter electrode15, a working electrode 16, and a reference electrode 17, fortransmitting a working voltage for an electrochemical reaction from anelectrochemical meter 18 to the container 12 and again transmitting theelectric parameter to the electrochemical meter 18 after the analytecontained in the fluid sample 11 undergoes an electrochemical reactionso that the electrochemical meter 18 can process a numerical analysisand then display the result thereon.

4. An electrochemical meter 18 for providing the working voltage (orcurrent) needed by the electrochemical reaction and measuring theelectric parameter (output voltage or current) produced by theelectrochemical reaction to record, or process the numerical analysisand display the testing data.

Meanwhile, plural testing electrodes can only include the counterelectrode and the working electrode or further include a referenceelectrode. Moreover, a detecting electrode could be included as a fourthelectrode. The number of the plural testing electrodes is variedaccording to the requirement of the electrochemical reaction.

The electrodes of different functions are made of different materials.In the laboratory, the counter electrode 15 is made of any conductivematerial, however the lower the conductive resistance the better theeffect, such as a copper, a silver, a nickel, a graphite, a carbon, agold, a platinum or other conductive materials, or can be a conductivemembrane electrode formed by printing a carbon paste or a silver paste.The most common structure of the reference electrode 17 is a modifiedelectrode 171 produced by means of printing or electroplating an Ag/AgClfilm. Because the electric potential of the Ag/AgCI film is quitestable, it is extensively used as the reference electrode.

The selection of the working electrode 16 is more complex and can besorted as two types, one is an electron-transfer mediator modifiedworking electrode and the other is a metal-catalyzed electrode. Theelectron-transfer mediator modified working electrode has a chemicalreagent immobilized thereon, wherein the chemical reagent includes anenzyme (such as a glucose oxidase) and a redox mediator (such as apotassium ferricyanide which is extensively used in the glucose testingpiece). The enzyme and the analyte will react with each other to producea new chemical compound (such as H₂O₂), the electrons generated from theredox reaction between the mediator and H₂O₂ is utilized to produce anelectric signal, and through the electrode, the electric parameter canbe outputted. The main purpose of this kind of electrode is only simplya conductor and is not involved in chemical catalysis. However, thematerial of the electrode should be selected specifically to avoid achemical reaction with the fluid sample 11 or the chemical reagent 14thereby interfering with the result.

The electrode without the chemical interference should be made of aninert conductive material, which is generally a noble metal (such as agold, a platinum, a palladium, or a rhodium), or a carbon containingmaterial (such as a carbon based screen printing electrode or a graphitebar). Furthermore, because carbon and the noble metal have no chemicalreactivity in a low temperature, the chemical interference would takeplace. However, because the noble metal is more expensive, the carbonmade electrode is usually applied as the electron-transfer mediatormodified working electrode.

As to the metal-catalyzed electrode, it is made of a material which willdirectly and electrochemically reacts with the chemical reagent, theanalyte, or the derivatives thereof, and has an ability of directcatalysis or a function of a single selectivity for the analyte. Thus,the mediator is not needed to add to the chemical reagent. This kind ofelectrode, not like the electrode only needs to be made of a chemicallyinactive metal, is generally made of a material that must have anability to catalyze the reaction. Therefore, the material thereof shouldnot be limited to be a noble metal but matched with the analyte, such asa copper, a titanium, a nickel, a gold, a platinum, a palladium, or arhodium . . . etc., (for example, a rhodium electrode has an excellentability to directly catalyze H₂O₂).

The two types of metal electrodes described above both have a high costof the material and the processes when being formed under conventionalmanufacturing methods. This is especially true regarding the noblemetal. Consequently, although the noble metal has a better stability, itcannot be the mainstream of the disposable medical treatment testing infamily. Nowadays, the biggest requirement of the biosensor is themedical treatment in family for a blood glucose, a uric acid or acholesterol . . . etc. And, the electrode used by these biosensorsmostly belongs to the electron-transfer mediator modified workingelectrode, and thus the disposable testing sheet of the biosensor canhave the carbon base screen printing electrode printed thereon forreducing the cost, as described in U.S. Pat. No. 5,985,116, which is atypical example.

Please refer to FIG. 2 which shows the example described in U.S. Pat.No. 5,997,817. In this patent, two conductive metal tracks 201 and 202both coated by a palladium are fixed on an insulative backing 203 withan identical size for being the metal electrode of the sensor. A workingelectrode 204 and a counter electrode 205, electrode leads 206 and 207,and signal output terminals 208 and 209 are all integrally formed bypalladium. However, the positions do necessarily be formed by palladiumare only two tiny sections of the working electrode 204 and the counterelectrode 205, and the other portions can only be formed by materialshaving a conductive characteristic rather than noble metal-palladium.

Further refer to FIG. 3 in which shows the example described in EP 1 098000 and is another manufacturing method for the metal electrode. In thispatent, an insulation sheet 301 previously injection molded haspositions of a pattern 302 surrounded by recesses and islands 306, anelectrode lead 303, and output terminals 304 and 305. Then, metallicdeposit proceeds to deposit a metal layer on the surface of plasticinsulation sheet. Due to all the surface of the insulation sheet beingcovered by deposited metal, an additional process has to be proceededfor removal of metal layer on the islands and remaining the patterns,the electrode leads and the output terminals. Thus, this method has ahigh cost and is only suitable for the electrode only formed by one kindof metal.

According to the technical defects described above, for reducing themanufacturing cost of the metal electrode in the disposable sensor stripand overcoming the problem of wasting the noble metal, the applicantdevoted himself to develop a “structure and manufacturing method ofdisposable electrochemical sensor strip” through a series ofexperiments, tests and researches. In addition to effectively solvingthe wasting problem of the noble metal in prior arts, the electrodesaccording to the present invention can be formed or modified in advancerespectively in different electroplating containers in a great quantity,and then be assembled to an isolating sheet for reducing manufacturingtime thereof.

Furthermore, in addition to be employed as the noble metal electroderequiring no chemical interference, the metal electrode according to thepresent invention can also be employed as the metal-catalyzed electrodewhich has a direct catalyzing function. And, the disposable electrodeand the sensor according to the present invention can be applied to allkinds of electrochemical testing electrodes, biosensors, biochemicalanalyte sensors for fluid (e.g., testing strips for a sewage, apesticide content, a heavy metal ingredient etc.), all kinds ofdomestically medical treatment testing strips (e.g., testing strips fora blood glucose, a uric acid, and a cholesterol).

SUMMARY

It is an object of the present invention to form a metal film on aconductive raw material for reducing the amount of noble metal appliedin the metal electrode of a disposable sensor strip.

It is another object of the present invention to provide metalelectrodes which can be formed and modified respectively in differentelectroplating containers in a great quantity in advance and then beassembled to an isolating sheet for reducing the manufacturing timethereof.

It is a further object of the present invention to provide a metalelectrode which can be mounted in a through hole of an isolating sheet,wherein an area of the through hole is an area of a working surface ofthe metal electrode. Additionally, the accurate area of the through holecan be achieved easily from the massive productivity of relevantindustrial methods, and a stable working surface of the metal electrodewas acquired simultaneously. And, because the testing signal produced bythe sensor is in proportion to the electrode area, the present inventioncan therefore substantially increase the accuracy of reproducibility ofthe electrochemical sensor.

It is an additional object of the present invention to employ a tenon onan isolating sheet for being fixed in a notch of a measuring device.

In accordance with an aspect of the present invention, a disposableelectrochemical sensor strip includes an isolating sheet having at leasta through hole, at least a conductive raw material mounted in thethrough hole, a metal film covering on the conductive raw material toform an electrode, which comprises an electrode working surface forprocessing an electrode action, and an electrode connecting surface, atleast a printed conductive film mounted on the isolating sheet andhaving a connecting terminal for being electrically connected to theelectrode connecting surface, and a signal output terminal foroutputting a measured signal produced by the electrode action.

Preferably, the conductive raw material of the sensor strip is metallicso as to form a metallic electrode with the metal film.

Preferably, the conductive raw material has a material selected from agroup consisting of a copper, a brass, an oxygen-free copper, a bronze,a phosphorized copper, a nickel silver copper and a beryllium copper.

Preferably, the sensor strip further includes a chemical reagent mountedon the electrode working surface for detecting an analyte throughreacting with the analyte contained in a fluid sample so as to producethe measured signal which is then outputted through the signal outputterminal.

Preferably, the electrode forms an electrode area in the through holewhose area is an area of the working surface for processing theelectrode action and transmitting the measured signal.

Preferably, the printed conductive film is formed by printing aconductive paste on the isolating sheet so as to form the signal outputterminal and the connecting terminal which is covered on the electrodeconnecting surface for electrically connecting with the electrode.

Preferably, the conductive paste is a conductive adhesive containing amaterial selected from a group consisting of a carbon, a silver, acopper, a nickel, an aluminum, a gold, a stainless steel and acombination mixture thereof.

Preferably, the strip further includes an insulating layer covered onthe printed conductive film.

Preferably, the metal film is made of a material selected from a groupconsisting of gold, platinum, rhodium, ruthenium, iridium, silver,copper, nickel, titanium, chromium, iron and aluminum.

Preferably, the conductive raw material of the sensor strip is one of acarbon-including conductive plastic compound, a metal-includingconductive plastic compound and a plastic material undergone with aconductive coating treatment.

Preferably, the conductive raw material of the sensor strip is modifiedby the metal film through a device selected from a group consisting ofan electroplating device, an immersion plating device (chemical platingwithout electrifying), a metal deposition device, a printing device, ametal spraying device.

Preferably, the electroplating device holds an electroplating liquidcontaining a metal ion for coating the metal film on the conductive rawmaterial.

Preferably, the conductive raw material is pre-modified with the metalfilm to form the electrode and then putted in the through hole of theisolating sheet.

Preferably, the conductive raw material is pre-putted in the throughhole of the isolating sheet and then modified with the metal filmthrough one of the electroplating device, the immersion plating device,the metal deposition device, the printing device, and the metal sprayingdevice so as to form the electrode in the through hole.

Preferably, the metal film has a thickness ranged from 0.02520 μm.

Preferably, the through hole and the conductive raw materialrespectively have a shape selected from a group consisting of a circularform, a rectangular figure and an annular shape and are engaged witheach other.

Preferably, the isolating sheet has two through holes whose bottoms arejoined together to form a U-shaped recess for engaging with theconductive raw material having a U-shaped cross section, the metal filmis coated on the conductive raw material in the U-shaped recess forforming the electrode with the electrode working surface in one leg ofthe U-shaped recess and the electrode connecting surface in another legof the U-shaped recess, which are at the same side with respect to theisolating piece, so that the electrode working surface, the electrodeconnecting surface and the printed conductive film are formed at thesame side of the isolating sheet.

Preferably, the through hole is a first through hole, the conductive rawmaterial is a first conductive raw material, the printed conductive filmis a first printed conductive film, the metal film is a first metalfilm, and the electrode is a first electrode to serve as a workingelectrode.

Preferably, the sensor strip further includes a second conductive rawmaterial mounted in a second through hole of the isolating sheet, asecond metal film modified on the second conductive raw material to forma second electrode which comprises a second electrode working surfacewhich serves as a counter electrode and a second electrode connectingsurface, and a second printed conductive film mounted on the isolatingsheet and having a second connecting terminal which is electricallyconnected with the second electrode connecting surface, and a secondsignal output terminal.

Preferably, the sensor strip further includes a third conductive rawmaterial mounted in a third through hole of the isolating sheet, a thirdmetal film modified on the third conductive raw material to form a thirdelectrode which comprises a third electrode working surface which servesas a reference electrode and a third electrode connecting surface, and athird printed conductive film mounted on the isolating sheet and havinga third connecting terminal which is electrically connected with thethird electrode connecting surface, and a third signal output terminal.

Preferably, the third metal film is a silver metal film, which isimmersion plated in a chemical solution, electroplated in a chemicalsolution or printed by an AgCl paste thereon through a printing deviceso that the silver metal film is modified into an Ag/AgCl referenceelectrode.

Preferably, the isolating sheet has a flowing recess located at an edgeportion above the electrodes for providing a fluid sample a space toflow therein, the flowing recess has a fluid inlet located at a side ofthe isolating sheet, the fluid inlet, the flowing recess and the throughholes are integrally formed, a covering layer is covered on the flowingrecess of the isolating sheet for forming a capillary channel and ameasuring section by cooperating with the fluid inlet and the flowingrecess, and the flowing recess further comprises a capillary vent forforming the capillary channel by cooperating with the fluid inlet.

Preferably, the counter electrode and the working electrode form anelectrode assembly and a space above the electrode assembly and underthe measure region is provided to position therein a chemical reagentwith an even thickness.

Preferably, the isolating sheet has a protruding spacer for raising thecovering layer and separating the fluid sample from an adhesive on thecovering layer.

Preferably, the counter electrode and the reference electrode are bothprinted electrodes on the isolating sheet, and the working electrode isa metal electrode which is modified from the conductive raw material andmounted in the through hole of the isolating sheet.

Preferably, the first electrode further comprises a modified layerimmobilized thereon for forming a modified electrode.

In accordance with another aspect of the present invention, a disposableelectrochemical sensor includes an isolating piece having at least athrough hole, at least a conductive raw material mounted in the throughhole, and a metal film coated on the conductive raw material for formingan electrode which comprises an electrode working surface for processingan electrode action, and a signal output terminal for outputting ameasured signal.

Preferably, the sensor further includes a chemical reagent mounted onthe electrode working surface for detecting an analyte in a fluid samplethrough reacting with the analyte so as to generate the measured signalwhich is then outputted through the signal output terminal.

Preferably, the isolating piece comprises a tenon which is fixed in anotch of a measuring device for placing the sensor on an exact testingposition of the measuring device.

Preferably, the electrode comprises a signal output point for beingconnected to a signal connecting point of the measuring device, theisolating piece has a measuring recess located at a portion above theelectrode for measuring a fluid sample, the measuring recess and thethrough hole are integrally formed, a meshed piece is mounted on themeasuring recess for filtering an impurity in the fluid sample, theelectrode and the chemical reagent are positioned under the meshed piecefor forming a measuring region, a covering layer is covered on themeshed piece and adhered to the isolating piece for avoiding the meshedpiece from escaping from the measuring recess, and the covering layercomprises an opening for dropping therein the fluid sample.

Preferably, the signal output terminal of the electrode has a rivetjoint, the sensor strip further comprises a metallic thin strip mountedon the isolating piece and having an output terminal and an electrodeconnecting hole electrically retaining therein the rivet joint.

In accordance with a further aspect of the present invention, adisposable electrochemical sensor strip includes an isolating sheethaving at least a recess, at least a metal electrode mounted in therecess and having an electrode working surface for processing anelectrode action and a signal output terminal for outputting a measuringsignal produced by the electrode action.

Preferably, the sensor strip further includes a metal film integrallyformed with the metal electrode.

Preferably, the sensor strip further includes a conductive raw materialwhich is integrally formed with the metal film and the metal electrode.

In accordance with an another aspect of the present invention, adisposable electrochemical sensor includes an isolating piece having atleast a through hole, at least a metal electrode mounted in the throughhole and having an electrode working surface and an electrode connectingsurface so as to process an electrode action through the electrodeaction, and at least a printed conductive film mounted on the isolatingpiece and having a conductive connecting surface electrically contactingwith the electrode connecting surface and a signal output terminaloutputting a measured signal produced by the electrode action.

Preferably, the metal electrode is a copper electrode.

In accordance with an another aspect of the present invention, adisposable electrochemical sensor strip includes an isolating sheethaving at least a through hole, and at least a metal electrode mountedin the through hole and having an electrode working surface forprocessing an electrode action and a signal output terminal foroutputting a measured signal produced by the electrode action.

Preferably, the isolating sheet comprises a tenon fixed in a notch of ameasuring device for positioning the strip on the measuring device.

In accordance with an additional aspect of the present invention, amethod for manufacturing a disposable electrochemical sensor stripincludes steps of providing an isolating piece having at least tworecesses, preparing a conductive raw material assembly comprising afirst and a second conductive raw material, forming a modified electrodethrough modifying the first conductive raw material, and forming thedisposable electrochemical sensor strip through positioning the modifiedelectrode and the second conductive raw material in the at least tworecesses.

Preferably, the method further includes an electroplating procedure formodifying the first conductive raw material to form a metal film andobtain the modified electrode.

Preferably, the method further includes a printing procedure for formingat least a signal output terminal through printing at least a conductivefilm on the isolating piece to be electrically connected to an outputsignal of the electrode.

Preferably, the method further includes a chemical reagent immobilizingprocedure for modifying the electrode to obtain an enzyme electrode.

The above objects and advantages of the present invention will becomemore readily apparent to those ordinarily skilled in the art afterreviewing the following detailed descriptions, and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a three-dimensional view of the basic electrochemicalsensor equipment in the prior arts.

FIG. 2 shows a disposable metal electrode sensor in the prior arts.

FIG. 3 shows a three-dimensional view of a disposable metal electrodesensor which is fabricated by a metal deposition in the prior arts.

FIGS. 4(a)-(d) respectively, show a front view, a reverse view, adecomposed front view, and a schematic view of a conductive raw materialmodified by a metal film of the electrochemical sensor strip having onesingle electrode in a preferred embodiment according to the presentinvention.

FIGS. 5(a)-(b) respectively, show a front view and a decomposed frontview of the electrochemical sensor strip having one single electrode ina preferred embodiment according to the present invention.

FIGS. 6(a)-(c) respectively, show a front view, a reverse view, and adecomposed front view of the electrochemical sensor strip having onesingle electrode in a preferred embodiment according to the presentinvention.

FIGS. 7(a)-(b) respectively, show a decomposed front view and adecomposed reverse view of the electrochemical sensor strip having onesingle electrode in a preferred embodiment according to the presentinvention.

FIGS. 8(a)-(b) respectively, show a structural front view and adecomposed front view of a modified electrode of a single electrodeaccording to the present invention.

FIG. 9 shows a schematic view of an example employing a combination ofthe single electrode and modified electrode according to the presentinvention.

FIGS. 10(a)-(b) respectively, show a front view and a decomposed frontview of the electrochemical sensor strip having two electrodes in apreferred embodiment according to the present invention.

FIGS. 11(a)-(b) respectively, show a front view and a decomposed frontview of the electrochemical sensor strip having three electrodes in apreferred embodiment according to the present invention.

FIG. 12 shows a schematic view of an example employing the sensor striphaving three electrodes according to the present invention.

FIGS. 13(a)-(d) respectively show a front view, a reverse view, adecomposed front view, and a schematic view of a conductive raw materialmodified by a metal film of the electrochemical sensor strip having acapillarity channel (which is suitable for micro-liter fluid samples) ina preferred embodiment according to the present invention.

FIG. 14 shows a front schematic view of an example employing acombination of the sensor strip and a measuring device according to thepresent invention.

FIGS. 15(a)-(c) respectively show a front view, a reverse view, and adecomposed front view of the electrochemical sensor strip having threeelectrodes in another preferred embodiment according to the presentinvention.

FIGS. 16(a)-(c) respectively show a front view, a reverse view, and adecomposed front view of the electrochemical sensor strip having threeelectrodes in further another preferred embodiment according to thepresent invention.

FIGS. 17(a)-(b) respectively, show a reverse view and a decomposed frontview of the electrochemical sensor strip having a capillarity channel(which is suitable for micro-liter fluid samples) in another preferredembodiment according to the present invention.

FIGS. 18(a)-(c) respectively, show a front view, a decomposed frontview, and a reverse view of the sensor strip in a preferred embodimentaccording to the present invention.

FIG. 18(d) shows a schematic front view of a combination of the sensorstrip and a measuring device in a preferred embodiment according to thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The present invention will now be described more specifically withreference to the following embodiments. It is to be noted that thefollowing descriptions of preferred embodiments of this invention arepresented herein for purpose of illustration and description only; it isnot intended to be exhaustive or to be limited to the precise formdisclosed.

Please refer to FIGS. 4(a)-(c) illustrate the structure of a disposableelectrochemical sensor strip having one single electrode according tothe present invention. The strip includes an isolating sheet 401 (socalled an insulating substrate) having a through hole 402. At least aconductive raw material 403 is mounted in the through hole 402 and iscoated by a metal film 404 so as to form an electrode 411, wherein theelectrode 411 includes an electrode working surface 409 and an electrodeconnecting surface 408. The electrode working surface 409 is employed toprocess an electrode action (namely, to be an electrode). Moreover, atleast a printed conductive film 410 whose thickness is ranged from 1.0μm to 20 μm having a connecting terminal 405 and a signal outputterminal 406 is printed on the isolating sheet 401, wherein theconnecting terminal 405 is electrically connected to the electrodeconnecting surface 408 and the signal output terminal 406 is employed tooutput a measured signal generated by the electrode action. Meanwhile,the conductive raw material 403 of the sensor strip can be made of ametal and then be coated by the metal film 404 to form a metal electrode411.

Furthermore, the sensor strip includes a chemical reagent 414 mounted onthe electrode working surface 409 of the metal electrode 411 so as toform an enzyme electrode 413 for examining an analyte in a fluid sample.The chemical reagent 414 reacts with the analyte to generate a measuredsignal that is then outputted through the signal output terminal 406.Moreover, the electrode 411 of the sensor strip will form an electrodearea 412 in the through hole 402 for transmitting the measured signal.Namely, the isolating sheet 401 includes at least a through hole 402,the metal electrode 411 is formed by coating the metal film 404 on theconductive raw material 403 and tightly mounted in the through hole 402,the metal electrode 411 is peripherally mounted by the isolating sheet401 for only revealing the electrode working surface 409 and theelectrode connecting surface 408, and the electrode working surface isemployed to process the electrode action.

Meanwhile, a conductive film 410 having a connecting terminal 405 and asignal output terminal 406 is printed on the isolating sheet 401,wherein the connecting terminal 405 is electrically connected to theelectrode connecting surface 408 and the signal output terminal 406 isemployed to output a measured signal generated by the electrode action.An insulating layer 407 is covered on a reverse side of the isolatingsheet 401 so as to reveal only the signal output terminal 406 of theprinted conductive film 410. Therefore, the conductive areas except theelectrode working surface 409 can be isolated by the insulating layer407 and will not contact with the fluid sample in order to avoid anexamining accuracy from being influenced.

In this embodiment, the electrode material that really works is themetal film 404 made of a gold, a platinum, a palladium, a rhodium, aruthenium, an iridium, a silver, a copper, a nickel, a titanium, achromium, an iron and an aluminum. As to the conductive raw material403, it should be made of a conductive material which can tightlycombine with the metal film 404, so that the material can be anyconductive metal, any carbon-including conductive plastic compound, anymetal-including conductive plastic compound, or a plastic materialundergone with a conductive coating treatment.

The methods for covering the metal film 404 on the conductive rawmaterial 403 include an electroplating, an immersion plating, a metaldeposition, a metal spraying. The conductive raw material 403 can bepreviously putted in the through hole 402 and then be modified by themetal film 404, or, oppositely, the conductive raw material 403 canfirstly be modified by the metal film 404 and then be putted in thethrough hole 402. The best procedures of this embodiment are firstlyplating a noble metal film 404 on the conductive raw material 403through a mass plating method (namely putting many conductive rawmaterials 403 in one plating container) and then putting the coatedconductive raw material into the through hole 402. The conductive rawmaterial 403 can be made of a copper and an alloy thereof, such as abrass, an oxygen-free copper, a bronze, a phosphorized copper, a nickelsilver copper and a beryllium copper. Because the copper and the alloythereof are easily to form all kinds of electrode shapes and areconductive which is suitable for being modified by the metal film 404through the plating process. The conductive raw material 403 can be madeof the carbon-including conductive plastic compound by means of aninjection-molding process. And, the carbon-including conductive plasticcompound is conductive and suitable for being modified by the metal filmthrough the plating process.

Nowadays, “plastic electroplating” has become a mature technology, whichemploys an injection-molding process to form the shape of thenon-conductive plastic material 403 and further coats a conductive layeron the plastic material 403 for sequentially plating the metal film 404thereon. Generally, a nickel layer will be previously coated on theplastic material, and then a needed metal film 404 is coated thereon.

The material of the printed conductive paste for forming the printedconductive film 410 can be a conductive adhesive containing a carbon, asilver, a copper, a nickel, an aluminum, a gold, a stainless steel and acombination mixture thereof, and the thickness of the printed film isranged from 1.0 to 20.0 μm. The material of the isolating sheet 401 canadopt a polyvinyl chloride (PVC), a polypropylene (PP), a polycarbonate(PC), a polybutylene terephthalate (PBT), a polyethylene terephthalate(PET), a modified polyphenylene oxide (PPO) or an acrylonitrilebutadiene styrene (ABS).

The thickness of the isolating sheet 401 is ranged from 0.2 mm to 3.0mm. The conductive raw material 403 can be a circular form, arectangular figure and an annular shape and has a thickness less thanthat of the isolating sheet 401 ranged from 0.00 mm to 0.15 mm, forexample, the thickness of the isolating sheet is 0.60 mm, the throughhole is circular with a diameter of 1.00 mm, and the raw material is acylindrical copper plate with a thickness of 0.50 mm and a diameter of1.02 mm. As the design described above, the diameter of the raw materialis lightly larger than that of the through hole so as to ensure thatthey can tightly engage with each other. The metal film 404 covered onthe electrode 411 can be a gold, a silver, a platinum, a rhodium, and apalladium, wherein when the metal film 404 of the electrode 411 is asilver, a silver chloride can be modified thereon for forming an Ag/AgClreference electrode. Certainly, the conductive raw material 403 can be acopper and simultaneously the metal film 404 also can be a copper,namely the electrode 411 is a pure copper electrode.

The through hole 402 on the isolating sheet 401 can be formed through aninjection-molding device, a punch press device, or a computerizeddrilling machine, and each of these mass producing methods can easilyachieve an accurate dimension of the through hole over 99.5%reproducibility. If the electrode 411 is mounted in the through hole402, it can firstly form the isolating sheet 401 having the through hole402 through injection-molding, punch pressing, or the drilling and thenput the electrode 411 in the through hole through a mechanicalprocessing device so that they can tightly engage with each other, or itcan put the electrode in a injection-molding device and inject a plasticmaterial therein for forming the isolating sheet and simultaneouslyengaging the electrode in the through hole.

Please refer to FIGS. 5(a)-(b) which illustrate another sensor striphaving one single electrode. The sensor strip includes an isolatingsheet 501 having a through hole 502, and a conductive raw material 503is putted in the through hole 502 so that they can tightly engaged witheach other, wherein the top 509 of the conductive raw material 503 isfurther coated by a metal film 504 so as to form a metal electrode(meanwhile, the conductive raw material 503 is a metal or acarbon-including conductive plastic compound). The metal electrodeincludes an electrode working surface 504 and an electrode connectingsurface 508, wherein the electrode working surface is employed toprocess an electrode action. Moreover, a conductive film 510 having aconnecting terminal 505 and a signal output terminal 506 is printed onthe isolating sheet 501, wherein the connecting terminal 505 iselectrically connected to the electrode connecting surface 508 and thesignal output terminal 506 is employed to output a measured signalgenerated by the electrode action. As to number 507, it represents aninsulating layer. The metal film 504 can be covered on the conductiveraw material 503 by an electroplating, an immersion plating, a metaldeposition, a metal spraying, or a metal printing.

According to another aspect of the present invention, the printedconductive film 410 can be replaced. Please refer to FIGS. 6(a)-(c)which illustrate another sensor strip having one single electrode. Inthis embodiment, a metallic thin strip 606 is employed to replace theprinted conductive film 410 in FIG. 4. The metal thin strip 606 has asignal output terminal 608 and a connecting hole 607, wherein theconnecting hole 607 is electrically connected to a rivet joint 604 on ametal electrode 603 for outputting a measured signal generated by theelectrode. As to number 605, it represents the electrode workingsurface. In this embodiment, the electrode can be a pure nickelelectrode and also a pure iron electrode.

Furthermore, the conductive raw material 403 in FIG. 4 can be replacedby an integral metal so that an integral metal electrode is formed andthe isolating sheet has to further form a recess for containing themetal strip, as shown in FIGS. 7(a)-(b). An integrally formed metalstrip 703 is employed to replace the metallic thin strip 606 and themetal electrode 603 in FIG. 6. The metal strip 703 includes an electrodeworking surface 704, an electrode lead 705, and a signal output terminal706, wherein the metal strip 703 can be integrally formed the electrodeworking surface 704, the electrode lead 705 and the signal outputterminal 706 by an injection-molding or a punch pressing which isdifferent from the printed conductive film 410 in FIG. 4. The isolatingsheet 701 includes a through hole 702 and a recess 707 for mounting themetal strip 703 so as to engage with each other. Regarding to theprocess of covering a metal film on the metal strip 703 (not shown inFIG. 7), it can be achieved by firstly covering the metal film on themetal strip 703 and then putting thereof in the through hole 702, orpreviously putting the metal strip 703 in the through hole 702 of theisolating sheet 701 and then covering the metal film thereon.

Please refer FIGS. 8(a)-(b) which illustrate a schematic view of amodified electrode. The metal electrodes in FIGS. 4-7 can be a workingelectrode or a counter electrode after properly selecting the conductiveraw material and the metal film. For applying the electrochemicalsensor, a modified layer 801 can be immobilized on the electrode 802through a specific procedure so that the pure electrode 802 will bemodified to be a modified electrode. For example, electrochemicallyimmersing the metal electrode 802 which is coated by a silver film intoa potassium chloride solution or printing the chlorine which willchemically react with the silver layer so as to form an Ag/AgClreference electrode, or immobilizing or coating a chemical reagent 414on the metal electrode 411 in FIG. 4 so as to form an enzyme electrode413, wherein the chemical reagent can be a complex including at least achemical material selected from a group consisting of an enzyme, a pHbuffer, a surfactant/surface active agent, a redox mediator, ahydrophilic polymer compound, or a hydrophilic filtering mesh.

The chemical reagent 414 on the enzyme electrode 413 is employed toreact with an analyte in a fluid sample so as to generate an electricmeasuring signal which will be outputted by the electrode 411 to ameter, such as the electrochemical measuring device 18 in FIG. 9, forbeing calculated to obtain the concentration of the analyte. When thechemical reagent 414 of the enzyme electrode 413 described abovecontains a redox mediator, the electrode will be an electro-transfermediator modified working electrode. When the electrode 413 is modifiedby a proper metal film, the electrode will be a metal-catalyzedelectrode, such as a platinum catalyzed electrode, a palladium catalyzedelectrode, a gold catalyzed electrode, a rhodium catalyzed electrode, ora copper catalyzed electrode. When the enzyme contained in the chemicalreagent 414 of the enzyme electrode 413 is glucose oxidase for examininghuman whole blood, the analyzing result of the fluid sample will be ablood glucose concentration of human blood. When the enzyme contained inthe chemical reagent 414 is a uricase for testing human whole blood, theanalyzing result of the fluid sample will be a uric acid concentrationin human blood. When the enzyme contained in the chemical reagent 414 isa cholesterol oxidase for testing human whole blood, the analyzingresult of the fluid sample will be a cholesterol concentration in humanblood.

Please refer FIG. 9 which illustrates an application of replacing thetraditional electrode in FIG. 1 through three disposable testing stripsaccording to the present invention. The conductive raw material of eachelectrode can be made of any conductive material and modified by a metalfilm to form a specific electrode. For example, employing threedisposable sensor strips of a gold film counter electrode 409, anAg/AgCI reference electrode formed by a silver film reference electrode802 and an Ag/AgCl modified layer 801, and an enzyme working electrode413 which is modified from a platinum film electrode for replacing thetraditional electrode in FIG. 1.

According to another aspect of the present invention, the recess 707 inFIG. 7 can be altered to receive only the through hole and not the metalconductive strip, as shown in FIGS. 10(a)-(b). FIGS. 10(a)-(b)illustrate a sensor strip having two electrodes in a preferableembodiment according to the present invention. The sensor strip includesan isolating sheet 1001 having a rectangular through hole 1002 and anannular through hole 1003 and a rectangular working electrode 1004 andan annular counter electrode 1006 are respectively mounted in thethrough holes 1002 and 1003 so as to engage with each other. Twoconnecting terminals 1007 of the conductive films are printed below theisolating sheet 1001 and two signal output terminals 1008 thereof areelectrically connected to the metal electrodes 1004 and 1006 foroutputting the measured signal generated by the electrode action. Achemical reagent 1005 is immobilized on the working electrode 1004 forreacting with an analyte in a fluid sample so as to produce an electricsignal which is then outputted to a device, such as the electrochemicalmeasuring device 18 in FIG. 1, through two electrode 1004, 1006,connecting terminals 1007 and output terminals 1008.

Please refer to FIGS. 11(a)-(b) which illustrate a sensor testing striphaving three electrodes in a preferable embodiment according to thepresent invention. The sensor strip includes an isolating sheet 1101having three though holes 1102, and a counter electrode 1105, a workingelectrode 1103 and a reference electrode 1104 are respectively mountedin three through holes 1102 so as to engage with each other. Threeconductive films 1108 are printed below the isolating sheet 1101, andthe three printed conductive films include signal output terminals 1109which are respectively connected to the metal electrodes 1103, 1104 and1105 for outputting the measured signal generated by the electrodeaction. An AgCl modified layer 1107 is coated on the reference electrode1104 for modifying the electrode 1104 into an Ag/AgCl referenceelectrode. A chemical reagent 1106 is immobilized on the workingelectrode 1103 for reacting with the analyte in a fluid sample so as togenerate an electric signal which will be outputted to a device 18through the electrode 1103, and the output terminal 1109.

Please refer FIG. 12 which illustrates an application of replacing thetraditional electrode in FIG. 1 with a disposable testing strip havingthree electrodes according to the embodiment in FIG. 11.

The embodiments shown in FIGS. 4-12 are suitable for testing medium tolarge amount samples. As to small amount samples (for example, thedisposable sensor strip for human blood only uses blood of several μL),the sensor strip therefor generally additionally has a structure forabsorbing the small amount sample in order to fully spread the sampleover all electrodes. And, if the electrodes are not fully covered by thefluid sample, a testing error might be caused. Please refer to FIGS.13(a)-(c) which illustrate an application employing a three electrodesensor strip having capillary channels according to the presentinvention. As shown in FIGS. 13(a)-(c), an adsorbing structure generallyincludes a capillary channel inlet 1308, a capillary channel 1314, and acapillary vent 1309, wherein the capillary channel 1314 is generally ameasuring section for the fluid sample.

When the fluid sample attaches the capillary channel inlet 1308, becausethe capillarity, the fluid will be automatically adsorbed by thecapillary channel 1314 until the measuring section is fully by thefluid. FIGS. 13-18 all are embodiments of sensor strips suitable forsmall amount samples. Firstly, FIG. 13 shows a three electrode sensorstrip having a capillary channel for examining the small amount sample.The sensor strip includes an isolating sheet 1301 having a fluidmeasuring recess 1314 (namely the capillary channel 1314). The bottom ofthe fluid measuring recess 1314 is a chemical reagent placing recess1306 for placing a chemical reagent 1307 so as to have a uniformdistribution thereof. Three through holes 1302 are positioned under theplacing recess 1306 for respectively receiving a working electrode 1303,a counter electrode 1305, and a reference electrode 1304.

The three electrodes 1303, 1304 and 1305 are engaged with the throughholes 1302 and are respectively covered by a metal film 1315 (as shownin FIG. 13(d), to form a metal electrode 1303, 1304 and 1305. Each ofthe electrodes 1303, 1304 and 1305 includes an electrode working surfaceand an electrode connecting surface wherein the electrode connectingsurface is utilized to process an electrode action. Meanwhile, threeprinted conductive films 1311 are positioned under the isolating sheet1301 and each of which includes a connecting terminal and a signaloutput terminal 1312. The connecting terminal of each printed conductivefilm 1311 is respectively and electrically connected to the electrodeconnecting surface of each electrode so as to output a measured signalthrough the signal output terminal 1312. Moreover, the fluid measuringrecess 1314 further includes a fluid inlet 1308 and the capillary vent1309, and a covering layer 1310 is positioned on the recess 1314 so asto compose a completed capillary adsorbing structure. Furthermore, theisolating sheet 1301 has two protruding spacers 1316 and 1317 forraising the covering layer 1310 and separating the fluid sample from anadhesive on the covering layer 1310.

The chemical reagent 1307 is positioned on the top of three electrodes1303, 1304 and 1305 for reacting with an analyte in the fluid sample soas to generate an electric signal which is then outputted to a device 18through the electrodes 1303, 1304, 1305 and the signal output terminal1312, wherein the electric signal is proportional to a concentration ofthe analyte and utilized to calculate a parameter of the analyte. Theconductive raw material 1313 of each electrode 1303, 1304 and 1305 canbe made of any conductive material. The metal film 1315 for covering theworking electrode 1303 can be a gold, the metal film 1315 for coveringthe reference electrode 1304 can be a silver which can be coated by asilver chloride layer to form an Ag/AgCl reference electrode, and themetal film 1315 for covering the counter electrode 1305 can be aplatinum.

Certainly, the metal film 1315 for covering the working electrode 1303can be a rhodium, a palladium, a ruthenium and a copper, and when themetal film is a copper, the metal substrate 1313 can also be a copper,namely the electrode is integrally formed by a copper.

According to the embodiment described above, the present invention alsoprovides a method for manufacturing a disposable electrochemical sensorstrip. The method includes providing an isolating sheet 1301 having atleast two recesses (through holes) 1302, preparing a conductive rawmaterial assembly including a first and a second conductive raw material(namely the conductive raw material 1313), modifying the firstconductive raw material to form a modified electrode 1315 (which can beelectroplated by a platinum to be a working electrode or beelectroplated by an Ag/AgCl layer to be reference electrode), andforming the disposable electrochemical sensor strip through positioningthe modified electrode and the second conductive raw material in tworecesses 1302. The method further includes an electroplating procedurefor covering a metal film on the first conductive raw material to formthe modified electrode 1315, and a step of immobilizing a chemicalreagent for obtaining an enzyme electrode.

Please refer to FIG. 14 which illustrates a combination of embodimentsof the sensor strips in FIGS. 13-17 and a device. An electrochemicaldevice 1401 includes an inlet 1402 which is employed to guide anelectrochemical sensor strip 1301 thereinto and the fluid sample will beadsorbed by the capillary channel inlet 1308. The device 1401 provides asufficient working potential needed by an electrochemical reaction toeach electrode and receives the measured signal outputted by theelectrode and displays an information after calculating the measuredsignal.

Please refer to FIGS. 15(a)-(c) which illustrate another embodiment ofthe present invention, applying a three electrode sensor strip havingthe capillary channel. This sensor strip includes an isolating sheet1501 having a first through hole 1503 for an electrode working surfaceand a second through hole 1504 for an electrode connecting surface,wherein the bottoms of the first and the second through holes are joinedtogether to form a U-shaped recess 1502 for engaging with an electrodehaving a U-shaped cross section. The U-shaped electrode 1505 includes anelectrode working surface 1506 and an electrode connecting surface 1507,both of which are located at the same side with respect to the isolatingsheet 1501. The electrode working surface 1506 is utilized to process anelectrode action.

Furthermore, a first printed conductive film 1508, a second printedconductive film 1514, and a third printed conductive film 1511 aresimultaneously printed on the isolating sheet 1501. The first printedconductive film 1508 having a connecting terminal 1509 and a workingelectrode output terminal 1510 is printed on the isolating sheet 1501and covered on the electrode connecting surface 1507, wherein theconnecting terminal 1509 is electrically connected to the electrodeconnecting surface 1507 for outputting the measured signal to the outputterminal 1510. The second printed conductive film 1514 having a counterelectrode output terminal 1516 and a second electrode terminal 1515 tobe a counter electrode 1515, and the third printed conductive film 1511having a reference electrode output terminal 1513 and a third electrodeterminal 1512 to be a reference electrode 1512, wherein the referenceelectrode 1512 can be modified by a silver chloride layer 1518 to forman Ag/AgCl reference electrode.

Meanwhile, an insulating layer 1519 having a C-shaped opening 1520 iscovered on the top of three conductive strips 1508, 1511, and 1514except the electrode working surface 1506 and the electrode outputterminal 1510. Then, a covering layer 1521 having a capillary vent 1522thereon is covered on the C-shaped opening 1520 for forming a completedcapillary adsorbing structure. Because of the cooperation between theU-shaped recess 1502 and the U-shaped electrode 1505 in this structure,the first conductive film 1508 for connecting the working electrode 1505can be printed on the isolating sheet 1501 together with the secondconductive film 1514 (with the counter electrode 1515) and the thirdconductive film 1511 (with the reference electrode 1512) at the sametime. Therefore, one printing procedure can be abridged.

Besides, a chemical reagent 1517 is positioned on the top of the workingelectrode 1505 for reacting with an analyte in a fluid sample so as togenerate an electric signal which is then outputted to the workingelectrode output terminal 1510 through the electrode 1505. Additionally,three printed conductive films 1508, 1511 and 1514 can be made of acarbon-including conductive paste or a silver paste. As to number 1523,it represents a fluid inlet.

In the embodiment described above, the working electrode 1505 is coveredby the metal film to form a working electrode having a good performance,and the electrode working surface 1506 formed in the first through hole1503 can be exactly obtained so as to significantly increase thequalitative reproducibility of the sensor. Regarding to the counterelectrode 1515 and the reference electrode 1512, because the materialand working surface thereof do not need to be as exact as the workingelectrode, they can be formed by the traditional printing methodthereby, reducing the cost.

Please refer to FIGS. 16(a)-(c) which illustrate further, anotherembodiment of a three electrode sensor strip having the capillarychannel according to the present invention. This embodiment is actuallyan alternation of the embodiment in FIG. 10 wherein the printedconductive film 1006 by an integrally formed conductive strip. In thisembodiment, three conductive strips, whose thicknesses range from 0.05mm to 1.00 mm respectively includes an electrode working terminal, anelectrode lead and an electrode output terminal and all are integrallyformed. The sensor strip include an isolating sheet 1601 having a firstplane 1602 and a second plane 1603, wherein the second plane 1603includes a first recess 1604 and a through hole 1605 thereon, as shownin FIG. 16(c), and, the through hole 1605 has another opening on thefirst plane 1602. Then, a first conductive strip 1606 which isintegrally formed is mounted in the first recess 1604 so as to engagewith each other, and the first conductive strip 1606 includes a firstelectrode output terminal 1608 and a first electrode terminal to be aworking electrode 1607.

Moreover, the first plane 1602 of the isolating sheet 1601 includes asecond recess 1611 and a third recess 1610 thereon for respectivelyreceiving a second conductive strip 1616 and a third conductive strip1612 mounted therein and engaged with each other. The second conductivestrip 1616 which is integrally formed includes a second signal outputterminal 1618 and a second electrode terminal to be a counter electrode1617, and the third conductive strip 1612 which is integrally formedincludes a third signal output terminal 1614 and a third electrodeterminal to be a reference electrode 1613, wherein the referenceelectrode 1613 can be modified by a silver chloride modified layer 1615so as to form an Ag/AgCl reference electrode. An insulating layer 1619having a C-shaped opening 1620 is covered on the top of two conductivestrips 1614 and 1618 except the working electrode 1607 and the electrodeoutput terminal 1608.

Then, a covering layer 1621 having a capillary vent 1622 thereon iscovered on the C-shaped opening 1620 for forming a completed capillaryadsorbing structure. A chemical reagent 1609 is positioned on the top ofthe working electrode 1607 for reacting with an analyte in a fluidsample so as to generate an electric signal which is then outputted tothe working electrode output terminal 1608 through the electrode 1607.As to number 1623, it represents a fluid inlet.

In addition, the embodiment in FIG. 16 can be altered by replacing thecounter electrode 1617 and the reference electrode 1613 by traditionalprinted conductive films printed on the insulating layer 1619, as shownin FIGS. 17(a)-(b). FIGS. 17(a)-(b) illustrate another applyingembodiment of a three electrode sensor strip having the capillarychannel according to the present invention. The sensor strip includes anisolating sheet 1701 having a fluid measuring recess 1702 thereon, and achemical reagent placing recess 1703 is positioned at the bottom of themeasuring recess 1702 for placing a chemical reagent 1708. Then, athrough hole 1704 is positioned under the placing recess 1703 forreceiving a first electrode 1707, namely a metal electrode, which isformed by covering a metal film on a conductive raw material. The firstelectrode 1707 includes a first electrode terminal as a workingelectrode 1707 and a first electrode connecting surface.

Moreover, a first printed conductive film 1718 is located below theisolating sheet 1701 and includes a connecting terminal 1719 and asignal output terminal 1720, wherein the connecting terminal 1719 iselectrically connected to the first electrode connecting surface foroutputting a measured signal through the signal output terminal 1720. Acapillary vent 1706 is located above the measuring recess 1702 and thenumber 1705 represents a fluid inlet. A covering layer 1716 ispositioned on the fluid measuring recess 1702 for forming a completedcapillary adsorbing structure. Furthermore, a second conductive film1709 and a third conductive film 1713 are printed on the covering layer1716, wherein the second conductive film 1709 includes a counterelectrode output terminal 1711 and a second electrode terminal to be acounter electrode 1710. The third conductive film 1713 includes areference electrode output terminal 1715 and a third electrode terminalto be a reference electrode 1714, which can be modified by a silverchloride modified layer 1712 so as to form an Ag/AgCl referenceelectrode.

Besides, a chemical reagent 1708 is positioned on the top of the workingelectrode 1707 for reacting with an analyte in a fluid sample so as togenerate an electric signal which is then outputted to the signal outputterminal 1720 through the electrode 1707. As to number 1717, itrepresents a C-shaped opening.

In this embodiment described above, the counter electrode 1710 and thereference electrode 1714 are printed on the covering layer 1716 foravoiding the working electrode from being polluted when modifying thereference electrode. And, because the isolating sheet 1701 and thecovering layer 1716 are separated when modifying, the working electrodewill not be contaminated.

Please refer to FIGS. 18(a)-(c) which illustrate another embodiment forapplying a three electrode sensor strip according to the presentinvention. In this embodiment, the signal output terminals in back ofthe metal electrodes are directly connected to the input connectingpoints on a measuring device. The sensor strip includes an isolatingsheet 1801 having a fluid measuring recess 1802 and three through holes1803, 1804 and 1805 are located at the bottom of the measuring recess1802 for respectively receiving three electrodes 1808, 1809 and 1810mounted therein and engaged with each other. Each of the electrodes1808, 1809 and 1810 include a signal output terminal 1813 and anelectrode working surface 1811 which is employed to process an electrodeaction.

A chemical reagent 1814 is positioned on the top of the electrodeworking surface 1811, a meshed piece 1815 is positioned on the top ofthe chemical reagent 1814 for protecting the chemical reagent 1814 andfiltering an impurity in a fluid sample and a covering layer 1816 havingan opening 1817 is covered on the meshed piece 1815 and connected to theisolating sheet 1801, wherein the opening 1817 serves as a fluid sampleinlet.

Besides, the isolating sheet 1801 further includes two tenons 1806 and1807 at two sides thereof so that the sheet 1801 can be slid into twonotches 1821 of a measuring device 1820 (as shown in FIG. 18(d)) so asto be fixed therein. After the sheet 1801 is slid into the notches 1821,the signal output points 1813 of the sensor strip will be directlyconnected with the signal connecting points 1822 of the measuring device1820 so as to complete the signal transmission. Thus, in thisembodiment, the printed conductive films on the isolating sheet are nolonger needed. As to the number 1818, it represents the backside of thesheet 1801.

If the metal electrode of a disposable sensor strip according to thepresent invention serves as a working electrode, it can be the firsttype: “electron-transfer mediator modified working electrode” and thesecond type: “metal-catalyzed electrode”. If the metal electrodeaccording to the present invention serves as the first type electrode,it only needs to employ the noble metal which has no chemicalinterference and does not need to be limited as a specific kind. Inother words, all of gold, platinum, palladium, and rhodium can beemployed. This kind of metal electrode according to the presentinvention utilizes a noble metal film to cover a conductive raw materialfor forming a metal electrode which is then mounted in a through hole ofan isolating sheet. Through this configuration, the used amount of thenoble metal used can be reduced and the time for manufacturing the metalelectrode also can be shortened. Furthermore, the sensor strip cantherefore, provide a good performance in the detecting reproducibilitybecause the electrode area thereof can be exactly obtained. If the metalelectrode according to the present invention serves as the second typeelectrode, the material of the working electrode should directlyparticipate in the electrochemical catalysis (namely it doesn't need toadd additional electron-transfer mediator therein). Thus, the materialshould be chemically matched with the chemical reagent and the analytein the fluid sample. For responding to different chemical reactions, themetal material will not be limited to be the noble metal and can be anykind of metal. For example, a copper electrode can serve as a workingelectrode for detecting H₂O₂. When the material selected is notexpensive, the conductive raw material and the metal electrode can bethe same for saving the coating procedure of the metal film. Hence, thetime for manufacturing the metal electrode still can be shortened, andthe sensor strip can therefore provide a good performance in thedetecting reproducibility because the electrode area thereof can beexactly obtained. Consequently, through the electrode structure and themanufacturing processes according to the present invention, thedisposable sensor strip can significantly reform the defects in theprior arts.

The main principle for designing the structure and manufacturing methodin the present invention is how to economize the noble metal material.Therefore, the present invention provides a cheap conductive rawmaterial (such as a copper cylinder having a diameter of 1.0 mm and athickness of 0.5 mm) for being further electroplated by a noble metalfilm (such as a rhodium film having a thickness of 0.0250.075 μm) forforming a noble metal electrode. Then, the electrode is mounted in thethrough hole of an isolating sheet so as to engage with each other andreveals only an electrode working surface and an electrode connectingsurface. The electrode working surface can process an electrode actionand a conductive film is further printed to connect to the electrodeconnecting surface for being a lead and an output terminal of theelectrode. In this structure, the noble metal material is only used forthe metal film which is further limited to only the electrode area inthe through hole. Thus, the amount of the noble metal can be reduced tobe minimum. In addition, if millions of raw materials of electrodes areelectroplated at a same time, and then putted into the trough holes ofan isolating sheet via a mechanical process, not only the noble metalmaterial but also the manufacturing cost can also be significantlyreduced.

The electrode according to the present invention is mounted in thethrough hole of an isolating sheet, and through the engagement from theisolating sheet, only an electrode working surface and an electrodeconnecting surface are revealed. Then, a conductive film is furtherprinted to connect to the electrode connecting surface for being a leadand an output terminal of the electrode. Therefore, the electrodeworking surface is not directly contacted by the conductive film so thatthe electrode surface is completely independent and decided by thethrough hole only so as to obtain an extremely accurate electrode area.Because the measured current is proportional to the electrode area, thepresent invention can greatly improve the reproducibility of theelectrochemical sensor strip.

Furthermore, in the present invention, the isolating sheet having thethrough hole thereon can be formed by an injection-molding method. Thesame as above, the injection-molding process can also integrally formother structures, such as the fluid sample inlet, the capillary channelrecess, the capillary convecting vent, the chemical reagent, placingrecess and the protruding spacer. Therefore, the number of theassembling elements, and the assembling error for many of theseelements, can be decreased, thereby reducing costs.

In view of the aforesaid, the present invention provides a novel mannerwhich utilizes a metal film to cover on a conductive raw material forreducing the amount of noble metal. Furthermore, the metal electrode ismounted in the through hole of the isolating sheet so that the time formanufacturing the disposable sensor strip according to the presentinvention can be significantly reduced. Therefore, the present inventionis extremely suitable for being used in industrial production.

While the invention has been described in terms of what is presentlyconsidered to be the most practical and preferred embodiments, it is tobe understood that the invention need not be limited to the disclosedembodiments. On the contrary, it is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the appended claims which are to be accorded with the broadestinterpretation so as to encompass all such modifications and similarstructures.

1. A disposable electrochemical sensor strip, comprising: at least aconductive raw material; a metal film covered on said conductive rawmaterial to form an electrode which comprises an electrode workingsurface for processing an electrode action, and an electrode connectingsurface; an insulation sheet having at least a through hole into whichthe conductive raw material and the metal film are mounted; and at leasta printed conductive film on said insulation sheet and having aconnecting terminal for being electrically connected to said electrodeconnecting surface, and a signal output terminal for outputting ameasuring signal produced by said electrode action, wherein saidelectrode forms an electrode area in said through hole whose area is anarea of said working surface for processing said electrode action andtransmitting said measured signal.
 2. The sensor strip according toclaim 1, further comprising a chemical reagent mounted on said electrodeworking surface for detecting an analyte through reacting with saidanalyte contained in a fluid sample so as to produce said measuredsignal which is then output through said signal output terminal.
 3. Thesensor strip according to claim 1, wherein said conductive raw materialis fully encapsulated in said metal film.
 4. A disposableelectrochemical sensor strip, comprising: a first conductive rawmaterial; a first metal film covered on said first conductive rawmaterial to form an electrode which comprises an electrode workingsurface for processing an electrode action, and an electrode connectingsurface, wherein said electrode forms an electrode area whose area is anarea of said working surface for processing said electrode action; aninsulation sheet having at least a first through hole into which thefirst conductive raw material and the first metal film are mounted; anda first printed conductive film on said insulation sheet and having aconnecting terminal for being electrically connected to said electrodeconnecting surface, and a signal output terminal for outputting ameasured signal produced by said electrode action and transmitting saidmeasured signal, wherein said electrode forms an electrode area in saidfirst through hole.
 5. The sensor strip according to claim 4 furthercomprising a second conductive raw material, a second metal film coatedon said second conductive raw material to form a second electrode whichcomprises a second electrode working surface which serves as a counterelectrode and a second electrode connecting surface and which is thenmounted in a second through hole of said insulation sheet, and a secondprinted conductive film mounted on said insulation sheet and having asecond connecting terminal which is electrically connected with saidsecond electrode connecting surface, and a second signal outputterminal.
 6. The sensor strip according to claim 5 further comprising athird conductive raw material, a third metal film coated on said thirdconductive raw material to form a third electrode which comprises athird electrode working surface which serves as a reference electrodeand a third electrode connecting surface and which is then mounted in athird through hole of said insulation sheet, and a third printedconductive film mounted on said insulation sheet and having a thirdconnecting terminal which is electrically connected with said thirdelectrode connecting surface, and a third signal output terminal.
 7. Thesensor strip according to claim 6, wherein said third metal film is asilver metal film which is immersion plated in a chemical solution,electroplated in a chemical solution or printed by an AgCl paste thereonthrough a printing device so that the silver metal film is modified intoan Ag/AgCl reference electrode.
 8. The sensor strip according to claim6, wherein said insulation sheet has a flowing recess located at an edgeportion above said electrodes for providing a fluid sample a space toflow therein, said flowing recess has a fluid inlet located at a side ofsaid insulation sheet, said fluid inlet, said flowing recess and saidthrough holes are integrally formed, a covering layer is covered on saidflowing recess of said insulation sheet for forming a capillary channeland a measuring section by cooperating with said fluid inlet and saidflowing recess to form a measure region, and said flowing recess furthercomprises a capillary vent for forming said capillary channel bycooperating with said fluid inlet.
 9. The sensor strip according toclaim 8, wherein said counter electrode and said working electrode forman electrode assembly and a space above said electrode assembly andunder said measure region is provided to position therein a chemicalreagent with an even thickness.
 10. A disposable electrochemical sensorstrip, comprising: at least a conductive raw material; a metal filmcoated on said conductive raw material for forming an electrode whichcomprises an electrode working surface for processing an electrodeaction, and a signal output terminal for outputting a measured signal,an insulation piece having at least a through hole into which theconductive raw material and the metal film are mounted; wherein saidelectrode forms an electrode area in said through hole whose area is anarea of said working surface for processing said electrode action andtransmitting said measured signal.
 11. The sensor strip according toclaim 10 further comprising a chemical reagent mounted on said electrodeworking surface for detecting an analyte contained in a fluid samplethrough reacting with said analyte so as to generate said measuredsignal which is then outputted through said signal output terminal. 12.The sensor strip according to claim 10 wherein said conductive rawmaterial and said metal film are fully received in said through hole.13. A disposable electrochemical sensor strip, comprising: at least ametal electrode having an electrode working surface for processing anelectrode action and a signal output terminal for outputting a measuringsignal produced by said electrode action; and an insulation sheet havingat least a recess into which the metal electrode in mounted, whereinsaid electrode forms an electrode area in said recess whose area is anarea of said working surface for processing said electrode action andtransmitting said measured signal.
 14. The sensor strip according toclaim 13 further comprising a metal film integrally formed with saidmetal electrode.
 15. The sensor strip according to claim 13 wherein saidmetal electrode is fully received in said recess.
 16. A disposableelectrochemical sensor strip, comprising: at least a conductive rawmaterial; a metal film coated on said conductive raw material forforming an electrode which comprises an electrode working surface forprocessing an electrode action, and a signal output terminal fordirectly outputting a measured signal; and an insulation piece having atleast a through hole into which the conductive raw material and themetal film are mounted.
 17. The sensor strip according to claim 16further comprising a chemical reagent mounted on said electrode workingsurface for detecting an analyte contained in a fluid sample throughreacting with said analyte so as to generate said measured signal whichis then directly outputted through said signal output terminal.
 18. Thesensor strip according to claim 16 wherein said conductive raw materialand said metal film are fully received in said through hole.
 19. Adisposable electrochemical sensor strip, comprising: at least aconductive raw material; a metal film coated on said conductive rawmaterial for forming an electrode for directly outputting a measuredsignal; and an insulation piece having at least a through hole intowhich the conductive raw material and the metal film are mounted. 20.The sensor strip according to claim 19 further comprising a chemicalreagent mounted on said electrode working surface for detecting ananalyte contained in a fluid sample through reacting with said analyteso as to generate said measured signal which is then outputted throughsaid signal output terminal.
 21. The sensor strip according to claim 19wherein the conductive raw material and the metal film are fullyreceived in the through hole.
 22. A disposable electrochemical sensorstrip, comprising: at least a conductive raw material; a metal filmcoated on said conductive raw material for forming an electrode whichcomprises an electrode working surface for processing an electrodeaction, and a signal output terminal for outputting a measured signal;and an insulation piece having at least a through hole into which theconductive raw material and the metal film are mounted, wherein saidelectrode and said insulation piece are simultaneously formed.
 23. Thesensor strip according to claim 22, wherein said electrode and saidinsulation piece are simultaneously formed through a molding deviceselected from the group consisting of an injection-molding device, apunch press device and a computerized drilling machine.
 24. The sensorstrip according to claim 22, wherein the conductive raw material and themetal film are fully received in the through hole.
 25. A disposableelectrochemical sensor strip, comprising: at least a conductive rawmaterial; a metal film coated on said conductive raw material forforming an electrode which comprises an electrode working surface forprocessing an electrode action, and a signal output terminal foroutputting a measured signal; and an insulation piece having at least athrough hole into which the conductive raw material and the metal filmare mounted, wherein said sensor strip comprises said insulation piecebeing the only one insulation piece therein.
 26. The sensor stripaccording to claim 25 further comprising a chemical reagent mounted onsaid electrode working surface for detecting an analyte contained in afluid sample through reacting with said analyte so as to generate saidmeasured signal which is then outputted through said signal outputterminal.
 27. The sensor strip according to claim 25 wherein theconductive raw material and the metal film are fully received in thethrough hole.